Genius Study Confirms More Sex Might Make You More Likely to Get Pregnant

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Photo: 145/B2M Productions/Corbis

According to conventional wisdom, if you're trying to have a kid, you should have as much sex as possible right before and during ovulation, when your ovaries release an egg. Some doctors recommend having more sex all month long — but how can that possibly help your fertility? Researchers at Indiana University think they've found the answer: It seems that having sex at all makes women's immune systems more receptive to pregnancy.

Remember, it's your immune system's job to keep out harmful visitors. "In order to protect itself, the body needs to defend against foreign invaders," lead author Tierney Lorenz said in a release. "But if it applies that logic to sperm or a fetus, then pregnancy can’t occur." Luckily, the human body is an amazing thing and we have certain helper T cells and immunoglobulins to tell the immune system, "Hold your fire, it's just sperm!" Now, it looks like sex is linked to that response.

For a pair of studies published in Fertility and Sterility and Physiology and Behavior, researchers looked at antibodies in saliva samples from 30 healthy women, 16 of whom were sexually active and 14 of whom were abstinent. They found that, during the luteal phase of the cycle, when the uterine lining thickens to prepare for implantation of a wee embryo, the sexually active women had higher levels of those helper T cells and immunoglobulins. Meanwhile, there were no shifts in immune response over the course of the abstinent women's cycles. "The sexually active women's immune systems were preparing in advance to the mere possibility of pregnancy," Lorenz noted.

This is great news for people trying to get pregnant. And it's just as great as a PSA for people who aren't trying to get pregnant: Birth control is your friend.